Counter circuit and driver therefor



J. CULLIS, JR

COUNTER CIRCUIT AND DRIVER THEREFOR Filed June 22, 1960 Sept. 1, 1964 INVEN TOR.

A 7'7'ORNE Y mw ww m i JOHN 0ULLI$,JR. 64 @1511 United States Patent3,147,398 COUNTER CIRCUIT AND DRIVER THEREFQR John Cullis, Jr.,Plainiieid, N.J., assignor to Burroughs Corporation, Detroit, Mich, acorporation of Michigan Filed June 22, 1960, Ser. No. 37,987 6 Claims.(Cl. 31584.6)

This invention relates to electronic counters and particularly todriving circuits for counters of the type using a multi-positionelectron beam switching tube.

The present invention is particularly useful with counting tubes of thetype known as magnetron beam switching tubes, for example type 6700tubes. This type of tube has been used in many counting circuits, and,in general, such circuits have operated well, particularly for highspeed counting. However, by comparison with the present invention, thesecounters have been comparatively complicated. For one thing, thesecounter circuits used flipflops to drive the beam switching tubes, and,in some instances, the circuitry was further complicated by theinclusion of cathode follower or other circuits as part of the drivingcircuitry,

The principles and objects of the present invention are concerned withthe provision of an improved electronic counter circuit using multipleposition magnetron beam switching tubes and characterized by simplicityof circuit design and low cost.

In brief, the counter circuit of the present invention is particularlysuited for use with a ten-position magnetron beam switching tube of thetype including a central cathode surrounded by a plurality of groups ofelectrodes, each of which includes an output or target electrode whichreceives an electron beam and provides an output signal, a spadeelectrode which forms and holds an electron beam on its associatedtarget electrode, and a switching electrode which serves to switch anelectron beam from one position to the next. In the circuit, the targetelectrodes are connected in two sets, with the targets at theodd-numbered positions in one set and the targets at the even-numberedpositions in another set. The switching electrodes are similarlyconnected in two sets.

A first variable resistance path is coupled between one set of targetelectrodes and its associated group of switching electrodes, and asecond variable resistance path is similarly coupled between the otherset of target and switching electrodes. Each path includes a gaseousglow tube which determines the resistance of the path by its state, thatis, by whether it is on or oflf. A source of switching pulses is coupledto the two paths and each switching pulse aifects only one of the setsof switching electrodes, the set associated with the low resistancepath. When a beam is switched, glow tubes change state, the paths changetheir relative resistance andthe tube is prepared for the next switchingpulse.

The invention is described in greater detail by reference to the singlefigure of the drawing which is a schematic representation of a magnetronbeam switching tube as used in a counter circuit embodying theinvention.

The circuit described below is particularly suitable for use with amulti-position type 6700 magnetron beam switching tube. In actualconstruction, this type of tube is cylindrical in form and is shownschematically in linear form as tube 10 in the drawing. The tubeincludes an envelope 12 which contains a central longitudinallyelongated cathode 14 and ten groups of electrodes spaced radiallyequidistantly from the cathode and surrounding the cathode. The groupsof electrodes are shown numbered 0, 1, 2 9. Each group of electrodesincludes a generally U-shaped elongated spade electrode 16 and agenerally L-shaped target electrode 18 positioned so that each targetoccupies the space between adjacent spade electrodes. Each spadeelectrode serves to form and hold 3,147,398 Patented Sept. 1, 1964 anelectron beam on its corresponding target electrode. A geenrallyrod-like switching electrode 20 is also included in each group ofelectrodes and is positioned between one edge of each target electrodeand the adjacent spade electrode. The switching electrodes are known asswitching grids. An open-ended cylindrical permanent magnet shownschematically at 22 is provided surrounding the tube envelope andcoaxial therewith. The magnet provides an axial magnetic field which isutilized in conjunction with electric fields within the tube to form andswitch an electron beam from the cathode to each of the groups ofelectrodes. The direction in which the beam switches, that is clockwiseor counterclockwise, is always the same and is determined by theorientation of the electric and magnetic fields.

Briefly, in operation of tube 10, electrons emitted by the cathode areretained at the cathode if each of the spades, targets and switchinggrids carries its normal operating electrical potential. When a spade issuitably lowered in potential, an electron beam is formed and directedto the corresponding target electrode. The electron beam may be switchedfrom one target electrode to the next by suitably altering theelectrical potentials of a spade or switching grid. Under normaloperating conditions, Whenever electrode voltages are such that a beammight be supported at several positions, the beam will switch to themost leading position and lock in at this position.

For convenience, in the tube 10 as shown, the oddnumbered andeven-numbered groups of electrodes are shown grouped together. In thecircuit, the cathode 14 is coupled through a capacitor 24 to a source ofreference potential such as ground. The switching electrodes 20 areconnected in two sets, with the electrodes at the evennumbered positionsin one set and the electrodes at the odd-numbered positions in the otherset. The spade electrodes 16 are coupled through spade load resistors 26to a spade buss 28 which is connected in turn through a common spaderesistor 30 to a positive DC. voltage supply V of about 250 volts. Anysuitable zero-set circuit is provided for setting an electron beam atthe 0 position at the beginning of a counting cycle, if such is desired.One suitable zero-setting circuit comprises, for example, a switch 31connected between the 0 spade and ground. The switch 31 is normallyopen, but, when closed and the tube is cleared, it causes a beam to format the 0 position.

The target electrodes 18 are also connected in two sets, with thetargets at the even-numbered positions being in one set and the targetsat the odd-numbered positions being in the other set. All of theeven-numbered target electrodes are coupled through load resistors 32 toa buss 34 which is coupled in turn through a resistor 36 and capacitor38 in parallel to the positive DC. power supply V. The target electrodesat the odd-numbered positions are connected through load resistors 32'to a buss 34 which is connected through a resistor 36' and capacitor 38in parallel to the power supply V. Each target is also provided with aterminal 40 by which it may be connected to any suitable utilizationdevice such as a visual indicator tube, a printer, or the like.

According to the invention, means for driving the beam switching tubeincludes a first variable resistance path comprising a first voltageregulator tube 42 such as a neon tube having one electrode 44 connectedto the target buss 34 and the other electrode 46 connected through acapacitor 47 and a resistor 48 to a buss 50. The junction point 52 ofresistor 48 and capacitor 47 is coupled to the switching electrodes atthe even-numbered positions. The driving means also includes a secondvariable resistance path comprising a neon tube 42' which has oneelectrode 44' connected to the target buss 34' and the second electrode46' connected through a capacitor 47' and a resistor 48' to the buss 50.The junction point 52 of resistor 48' and capacitor 47 is coupled to theswitching electrodes at the odd-numbered positions. The buss 50 isconnected through a resistor 54 to ground and through a capacitor 56 toa. source 57 of negative input counting pulses which have an amplitudeof about 150 volts. The glow tubes 42 and 42 vary the resistances of thefirst and second paths, depending on their operating state, that is,whether they are on or olf. If a glow tube is on, the path is arelatively high resistance path, and if a tube is off, the path is arelatively low resistance path.

In operation of the circuit, if power is turned on without the formationof a beam in the tube 10, the voltage applied across the neon tubes 42and 42' is suflicient to cause both of them to be ignited and to passcurrent. At this time, the busses 34 and 34 carry a potential of about235 volts, and the potential at the electrodes 46 and 46 of tubes 42 and42' is about 175 volts. A beam may be formed at the position by closingthe zero-set switch 31. When a beam is formed at the 0 position, currentflow through the 0 target to the power supply provides a potential ofabout 175 volts at the target buss 34. This potential appears on thefirst electrode 44 of the neon tube 42. At the same time, a potential ofabout 160 volts appears on the second electrode 46 of tube 42 as aresult of current flow through the second neon tube 42'. Thus, with onlyabout volts applied across the first neon tube 42, this tube isextinguished.

The tube 10 is caused to perform a counting operation by the applicationof negative counting pulses of about 150 volts amplitude from the source57. The first pulse after the beam has been set at 0, when coupledthrough the capacitor 56 to the driving circuit of tube 10, sees a highresistance path, the one in which the neon tube 42 is glowing, and a lowresistance path, the one in which the neon tube 42 is extinguished.Accordingly, the greater portion of the pulse, as it flows into the highresistance path, is absorbed across resistor 48, and only a smallportion is coupled through capacitor 47 to the odd-numbered switchingelectrodes. This pulse is too small to affect the tube It), and in anycase, since the beam is in an evennumbered position, a pulse applied toan odd-numbered switching grid cannot switch the beam. However, in thelow resistance path, only a small portion of the input pulse is absorbedby resistor 48, and the greater portion of the pulse is coupled throughcapacitor 47 to the even-numbered switching grids, including, of course,the switching grid at the position to which the beam is flowing. Thispulse thus causes an electron beam to switch by one position into anodd-numbered position, position 1. Current flow through the target loadresistor at the 1 position then reduces the potential of the target buss34' and the first electrode 44' of the second neon tube 42' to such alevel that this tube is extinguished. At the same time, when currentflow to the 0 target is discontinued, the target buss 34 rises to about235 volts, which provides sufficient potential across the first neontube 42 to cause it to glow, In similar fashion, the next switchingpulse causes the electron beam to switch from the first position to thesecond, turns off the second neon tube 42, and turns on the first neontube 42.

The circuit of the invention thus provides a simple and inexpensivecircuit for driving a multi-position beam switching tube as a counter.

What is claimed is:

1. A counter circuit including an electron beam switching tube having acathode and a plurality of groups of electrodes; each group including atarget electrode which receives an electron beam and produces an outputsignal therefrom, a spade electrode which holds an electron beam on itsassociated target electrode, and a switching electrode which serves toswitch an electron beam n65; one group of electrodes to the next; saidtarget electrodes being connected in two sets with alternate targetsbeing connected in a set; the switching electrodes being connected intwo sets with alternate switching electrodes in a set; a first currentflow path in series with one set of target electrodes and including agaseous glow tube; and a second current flow path in series with theother set of target electrodes including a gaseous glow tube; said pathsalternately having high and low resistance; the path having lowresistance having its glow tube off and associated with the set oftarget electrodes which includes the target electrode receiving anelectron beam at any instant; the path having high resistance having itsglow tube on; and a source of switching pulses couple through separateimpedances to each of said glow tubes and through other separatecoupling impedances to said sets of switching electrodes.

2. A counter circuit including an electron beam switching tube having acathode and a plurality of groups of electrodes; each group including atarget electrode which receives an electron beam and produces an outputsignal therefrom, a spade electrode which holds an electron beam on itsassociated target electrode, and a switching electrode which serves toswitch an electron beam from one group of electrodes to the next; saidtarget elec trodes being connected in two sets with alternate targetsbeing connected in a set; the switching electrodes being connected intwo sets with alternate switching electrodes in a set; a first currentflow path in series with one set of target electrodes and coupled to theset of switching electrodes associated therewith; a second current flowpath in series with the other set of target electrodes and coupled tothe other set of switching electrodes; said paths being adapted toalternately have high and low resistance; the path having low resistancebeing associated with the set of target electrodes which includes thetarget electrode receiving an electron beam at any instant; and a sourceof switching pulses coupled to said paths for applying beam switchingpulses thereto through separate impedances, said source thus beingcoupled both to said glow tubes and to said sets of switching electrodesthrough voltage-dropping impedances.

3. A counter circuit including an electron beam switching tube having acathode and a plurality of groups of electrodes; each group including atarget electrode which receives an electron beam and produces an outputsignal therefrom, a spade electrode which holds an electron beam on itsassociated target electrode, and a switching electrode which serves toswitch an electron beam from one group of electrodes to the next; saidtarget electrodes being connected in two sets with alternate targetsbeing connected in a set; the switching electrodes being connected intwo sets with alternate switching electrodes in a set; a first pathincluding a first gaseous glow tube and an impedance coupled between oneset of target electrodes and a source of reference potential; couplingmeans coupling said path to the set of switching electrodes associatedwith said one set of target electrodes; a second path including a secondgaseous glow tube and an impedance coupled between the other set oftarget electrodes and said source of reference potential; coupling meanscoupling said second path to the other set of switching electrodes; anda source of beam switching pulses coupled through separate impedances toboth of said paths and adapted to aiiect only one set of switchingelectrodes with each switching pulse, the set of switching electrodesaffected being determined by the state of each glow tube and theresultant potential applied across each of said separate impedances andby the potential coupled to each set of switching electrodes.

4. A counter circuit including an electron beam switching tube having acathode and a plurality of groups of electrodes; each group including atarget electrode which receives an electron beam and produces an outputsignal therefrom, a spade electrode which holds an electron beam on itsassociated target electrode, and a switching electrode which serves toswitch an electron beam from one group of electrodes to the next; saidtarget electrodes being connected in two sets with alternate targetsbeing connected in a set; the switching electrodes being connected intwo sets with alternate switching electrodes in a set; a first currentflow path including a first gaseous glow tube coupled between one set oftarget electrodes and a source of reference potential; coupling meanscoupling said path to the set of switching electrodes associated withsaid one set of target electrodes; a second current fiow path includinga second gaseous glow tube coupled between the other set of targetelectrodes and said source of reference potential; coupling meanscoupling said second path to the other set of switching electrodes; anda source of beam switching pulses coupled to both of said paths andadapted to aifect only one set of switching electrodes with eachswitching pulse, the set of switching electrodes affected beingdetermined by the state of each glow tube and the resultant potentialapplied across each of said separate impedances and by the potentialcoupled to each set of switching electrodes.

5. A counter circuit including an electron beam switching tube having acathode and a plurality of groups of electrodes; each group including atarget electrode which receives an electron beam and produces an outputsignal therefrom, a spade electrode which holds an electron beam on itsassociated target electrode, and a switching electrode which serves toswitch an electron beam from one group of electrodes to the next; saidtarget electrodes being connected in two sets with alternate targetsbeing connected in a set; the switching electrodes being connected intwo sets with alternate switching electrodes in a set; a first pathincluding a first gaseous glow tube and an impedance coupled between oneset of target electrodes and a source of reference potential; couplingmeans coupling said path to the set of switching electrodes asociatedwith said one set of target electrodes; a second path including a secondgaseous glow tube and an impedance coupled between the other set oftarget electrodes and said source of reference potential; coupling meanscoupling said second path to the other set of switching electrodes; saidpaths being adapted to have relatively high or low impedance dependingon the state of its glow tube; and a source of beam switching pulsescoupled through separate impedances to both of said paths and adapted toaffect only one set of switching electrodes with each switching pulse,the set of switching electrodes affected being the set coupled to thepath which exhibits low impedance due to the state of its glow tube.

6. A counter circuit including an electron beam switching tubehaving acathode and a plurality of groups of electrodes arranged in a series andoccupying alternately even-number and odd-number positions in theseries; each group of electrodes including a target electrode whichreceives an electron beam and produces an output signal therefrom, aspade electrode which holds an electron beam on its associated targetelectrode, and a switching electrode which serves to switch an electronbeam from one group of electrodes to the next;

said target electrodes being connected in two sets with a first setincluding the target electrodes at the even-number positions and asecond set including the target electrodes at the odd-number positions;

the switching electrodes being connected in two sets with a first setincluding the switching electrodes at the even-number positions and asecond set includin the switching electrodes at the odd-numberpositions;

a first current flow path in series with said first set of targetelectrodes and including a first gaseous glow tube; a second currentflow path in series with said second set of target electrodes andincluding a second gaseous glow tube;

said first and second paths alternately being adapted to have relativelyhigh and low impedance depending on whether the glow tube therein is onor ofi, with the impedance being low when a glow tube is off and highwhen a glow tube is on;

said first glow tube being on in said first path including said firstset of target electrodes and said first set of switching electrodes whenan electron beam is flowing to a target electrode in said second set,said second glow tube being on in said second path including said secondset of target electrodes and said second set of switching electrodeswhen an electron beam is flowing to a target electrode in said firstset;

and a source of switching pulses coupled through separate impedances toeach of said first and second current fiow paths for applying beamswitching pulses thereto, with a switching pulse being applied to andaifecting only that set of switching electrodes associated with a targetelectrode which is receiving an electron beam and with a current flowpath having low impedance.

Medoff Aug. 26, 1958 Gardberg Jan. 12, 1960

1. A COUNTER CIRCUIT INCLUDING AN ELECTRON BEAM SWITCHING TUBE HAVING ACATHODE AND A PLURALITY OF GROUPS OF ELECTRODES; EACH GROUP INCLUDING ATARGET ELECTRODE WHICH RECEIVES AN ELECTRON BEAM AND PRODUCES AN OUTPUTSIGNAL THEREFROM, A SPADE ELECTRODE WHICH HOLDS AN ELECTRON BEAM ON ITSASSOCIATED TARGET ELECTRODE, AND A SWITCHING ELECTRODE WHICH SERVES TOSWITCH AN ELECTRON BEAM FROM ONE GROUP OF ELECTRODES TO THE NEXT; SAIDTARGET ELECTRODES BEING CONNECTED IN TWO SETS WITH ALTERNATE TARGETSBEING CONNECTED IN A SET; THE SWITCHING ELECTRODES BEING CONNECTED INTWO SETS WITH ALTERNATE SWITCHING ELECTRODES IN A SET; A FIRST CURRENTFLOW PATH IN SERIES WITH ONE SET OF TARGET ELECTRODES AND INCLUDING AGASEOUS GLOW TUBE; AND A SECOND CURRENT FLOW PATH IN SERIES WITH THEOTHER SET OF TARGET ELECTRODES INCLUDING A GASEOUS GLOW TUBE; SAID PATHS